Chiral symmetry breaking beyond BCS and theorem on the width of scalars

Abstract

We review chiral symmetry breaking at the BCS level, in the framework of chiral invariant quark models and in the Schwinger-Dyson formalism. We revisit the pi mass problem beyond the BCS level. We show a theorem on the masses, on the widths and on the q qbar content of the scalar mesons sigma and f0.